The present invention relates to a device and method for the gripping and or handling of tubular members. These tubular members vary widely in size, shape, thickness, function, orientation while in service, and industries served. They can be pipes, steel structures, columns, tubing, casing, culverts, pilings, caissons, pipelines, etc. A non-inclusive list of uses for the present invention includes:
1) A first use is in the construction of oil and gas wells where it is usually necessary to drill and line the well bore with a string of steel pipes commonly known as tubulars, casing, tubing, or generically as oil country tubular goods (“OCTG”).
2) A second use is in the abandonment or decommissioning of oil and gas wells where it is usually necessary to remove the steel pipes commonly known as tubulars, casing, tubing, or generically as oil country tubular goods (“OCTG”), steel structures, pilings, caissons and or pipelines
3) A third use is in anchoring connector systems for offshore drilling establishments. In deepwater drilling activities the use of floating drilling rigs is necessary. These drilling rigs may be in the form of semi-submersibles, spars, drill ships, etc. These drilling rigs must be anchored or tethered to the sea floor to remain in position. To accomplish this, suction anchors are deployed and placed onto the sea floor. Large ropes or chains must then be attached from the drilling rig to these anchors. Anchoring connectors are used to connect the ropes or chains to the anchors via ROV's. These anchoring connectors are far easier to attach in deep water or extreme depth conditions using large shackles or the like.
4) A fourth use is in the recovery of damaged or abandoned pipelines from the sea floor. These connectors provide a means to grip the pipeline while being manipulated by a ROY.
5) A fifth use is in the placement of columns for wind energy turbines.
6) A sixth use is in the erection of structures fabricated from tubular members such as offshore platforms, water towers, etc.
While not limiting in any way the intended use of the present invention, for purposes of description the use of the present invention as it relates to a device and method for facilitating the connection of tubulars used in the oil and gas exploration and extraction industries using a top drive will be presented to illustrate the elements of the present invention. More specifically, the invention will be described as it relates to a device and method for running tubulars into and or out of a well bore.
In the construction of oil or gas wells it is usually necessary to drill and line the well bore with a string of steel pipes commonly known as tubulars, casing, tubing, or generically as oil country tubular goods (“OCTG”). For purposes of this application, such steel pipes shall hereinafter be referred to as “tubular OCTG”. Because of the length of the tubular OCTG required, individual sections of tubular OCTG (tubular members) are typically progressively added to the string (tubular string) as it is lowered into or lifted out of a well from a drilling rig or platform. The section to be added or removed is restrained from falling into the well by some tubular engagement means, typically a spider or the like, and is lowered into the well to position the threaded pin of the tubular OCTG section adjacent the threaded box of the tubular OCTG in the well bore. The sections are then joined by relative rotation of the sections and the process repeated until such time as the desired total length has been achieved.
It is common practice to use a power tong to torque each connection to a predetermined torque in order to connect the sections of tubular OCTG. This traditional method and equipment types have been used extensively around the world for a period in excess of fifty years. While this method is in daily use it normally requires a large team of specialist personnel along with a plethora of equipment to successfully undertake this task. It is also a very dangerous task with personnel often having to be located on a small platform suspended up to 50 feet from the rotary table or drilling rig floor and the power tong tethered to a steel cable under high loads.
In more recent times, a top drive may be used; this is, a top drive rotational system used for drilling purposes. Where a top drive system is used to make up the connection, the use of a slip type elevator to restrain the section of tubular OCTG to be added may be problematic, due to the configuration of the top drive apparatus on the drilling platform. It is therefore known to make use of an apparatus connected to the top drive, which can be inserted into the interior of or around the exterior of a section of tubular OCTG to be added, and engaged therewith to hold the section in place. Such apparatus may comprise one or more toothed grapple/dies, which may be hydraulically operated to engage an inner or outer surface of the tubular OCTG. While this is an advancement over the traditional approach as it requires substantially less equipment, it does however have serious drawbacks in the form of potential damage it may cause to the outer or inner surface of the tubular OCTG. These grapple/dies also tend to be very sensitive to varying changes in tubular weight and diameters and therefore require a large resource of alternative sizes for each tubular OCTG size or weight to be run.
Secondly, as the grapple/dies tend to bite aggressively into the tubular OCTG and take no account of alignment issues it is possible to load one side of the grapple/dies while running the tubular OCTG into the well bore. The possibility of loading one side of the tubular OCTG can present serious consequences for the integrity of the tubular OCTG and its ability to withstand down-hole pressures in the borehole. This in turn may also result in premature failure of the grapple/dies or impede their ability to act correctly on the tubular OCTG.
Thirdly, as the grapple/dies tend to be suspended on the outside of the member for internal gripping tools with no means of constraint they can become a huge safety issue if the rotational drive is engaged whilst the probe is not inside the tubular OCTG. The centrifugal forces cause the grapple/dies to separate from the tool member, causing them to become entangled in the steel framework of the rig and potentially becoming dangerous objects falling from the derrick structure.
Fourthly, traditional methods of tool design permits the slip assemblies, bodies or inserts to potentially friction bond or become adhered to each other under heavy load conditions. This factor is due to the static frictional forces increasing; thereby displacing the lubricants between the sliding member surfaces. If these slip assemblies, bodies or inserts become frictionally adhered, this can cause serious problems, especially in a well control situation. It can cause the tubular OCTG or the slip assemblies, bodies or inserts to require to be mechanically separated by means of a cutting torch or other means.
Lastly in more recent designs the grapple/dies portion has been replaced by the adoption of ball and taper or rolling element and taper technology originally designed for anchor handling applications where a static or dynamic axial load is applied. In order to better understand the terminology and advantages of the present invention the definitions of a ball and rolling support are:
Ball—shape in which all surfaces are equidistant from its centroid with no limitation of rotation in any given plane or direction
Rolling Support—shape in which all surfaces are not equidistant from its centroid but with constraints can function as a rolling support in one plane or direction. The surfaces can be multi-faceted and or can be geometrically altered to fit a given profile with the ability to bear, hold, or support a load, mass, structure or part thereof
In mooring applications for offshore floating structures chain is widely used, usually as part of a system combining chain and rope, be it fiber or wire. Multiple connectors and chain are favored for mooring systems for several reasons:
It is rugged and less prone to damage than wire or fiber rope when used with topsides, catenary, or seabed equipment. It is also easy to handle and requires only standard topsides tensioning equipment                It is less prone to corrosion than wire rope        Chain weight per unit length is higher than wire rope for a given strength. So chain can be used mid-line as a clump weight to alter the catenary shape or as a ground line so that a smaller anchoring system can be used.        
While this method of multiple connectors or anchor stations has been successful in mooring connectors where a failure of one connector will most likely not have a serious impact on the other connectors and repairs can be expedited. Design safety factors for mooring connectors and or mooring chains are substantially lower than the International Standard ISO 13535 for Petroleum and natural gas industries—Drilling and production equipment—Hoisting equipment. When it comes to handling tubulars OCTG's where a single connector is used the failure of this single connector has the potential for catastrophic consequences.
A first disadvantage of previous attempts is in the design of the member containing the inclined or tapered ramps which include areas of deeper than necessary pockets as well as sharp corners. These pockets are used for assembly purposes in some previous attempts and for locating spring biasing devices in others. These pockets decrease the minimum cross sectional area. The minimum cross sectional area of the member containing the inclined ramps is a critical factor in determining the Safe Working Load rating and or capabilities for the gripping device. The International standard ISO 13535 for Petroleum and natural gas industries—Drilling and production equipment—Hoisting equipment requires that all hoisting equipment furnished under this International Standard shall be rated in accordance with a specific load rating based on the design safety factor. This is especially important for internal gripping devices where the device outside diameter is dictated by the internal diameter of the tubular OCTG to be run or pulled. Thus, the main cross sectional area of the load bearing member is vitally important and must be maximized by all means possible.
The design safety factor is specified as a multiplication formula for hoisting equipment whereby the specified minimum yield strength of the materials chosen must be tested between two and a quarter (2¼) and three (3) times the safe working load, then checked for functionality, fit and fully inspected for signs of failure. Thus, it is evident that in order to comply with the Safe Working Load Rating and Design Safety Factors hoisting tools must have the cross sectional area maximized to achieve the high load carrying capacities required of them.
A second disadvantage of previous attempts is that they were ineffective in providing the rotational torque capacity required for the make-up or break-out of said tubular OCTG. This is due to the self-engaging, spring biased, or gravity biased balls or rolling elements of current designs. Some embodiments of previous attempts utilize springs on individual balls or rolling elements to urge them down the inclined surface toward the shallow end causing them to protrude from the cage. This method of energizing the balls or rolling elements is ineffective in applying an adequate amount of preload force on the balls or rolling elements to create an indentation of sufficient size and depth to apply the required torque without slipping. These designs do not allow the operator the ability to hydraulically, pneumatically, or mechanically control these preload forces to create the required indentations for applying torque.
A third disadvantage of this previous attempts is in the design of the openings or slots and its role in applying torque. Previous attempts cage housing openings make no attempt to aid in the application of torque. It will be shown in the accompanying drawings that the design of the cage housing openings of the invention presented here make accommodations for aiding in the transmission of torque. The cage housing openings contain large surface areas on the flat sides to contact against the sides of the rolling supports for torque transmission. This cage housing can also be splined, keyed, or otherwise affixed to the member containing the inclined surfaces to allow relative axial movement while disallowing relative rotational movement. This feature allows torque to be transmitted from the member having the inclined surfaces, through the cage and rolling supports, to the tubular.
A fourth disadvantage of this previous attempts is the use of elongated slots where the length of the slot is substantially longer than the diameter of the ball or rolling element. When disengaging a gripping device utilizing these elongated slots, the cage housing must travel axially an excessive distance before the slot comes into contact with the ball or rolling element then must continue to travel axially to urge the ball or rolling elements up the inclined surface toward the deep end of the pocket and thus released position.
A fifth disadvantage of these elongated slots is the large cavity created between the elongated slots and the inclined surfaces. This cavity may become filled with debris or other materials than can inhibit or prevent the function of the gripping device.
A sixth disadvantage of the elongated slot design is that the slot must contain a means of retaining the ball or rolling element along the longer sides of the slot because the ball or rolling element must be allowed to travel the entire length of the slot. This is generally accomplished by having the width of the slot narrower than the diameter or width of the ball or rolling element. This aspect of the design prevents the sides or edges of a rolling element to protrude from the cage housing which limits the options for the shape of the rolling element. It is important to have the ability to change or modify the shape of the rolling elements to accommodate varying applications. The shape of the rolling element can also limit the range of outer or inner surface diameters which can be gripped with a given gripping device configuration.
A seventh disadvantage of the elongated slots is amount of material that is removed from the cage housing diminishing the structural integrity of the cage housing. Tools and equipment manufactured for service on a drilling rig must be very robust as they operate in extreme conditions. Transporting tools to or from a drilling rig, loading, and unloading of these tools, especially on an offshore location, as well as handling of these tools can create damages. Thus tool designs must account for these conditions of service.
A eighth disadvantage of previous attempts is the means of disengaging or releasing an internal gripping device during entry into a tubular whereby frictional forces acting upon the outer surface of the cage housing imposed from the internal surface of the tubular act to urge the cage housing in a direction such that the rolling elements move toward the deep end of the inclined surfaces, thus released position. This previous attempts design requires these frictional forces to function properly. This “dragging” of the cage housing produces wear on the cage housing as well as the internal surface of the tubular. This dragging can also cause damage to the internal tubular threads. Again, it will be evident from the accompanying drawings and descriptions that the present invention is superior in that it provides a hydraulic, pneumatic, or mechanical means of retracting or releasing the gripping device prior to entering a tubular. It is also a feature of this invention that the rolling supports are not allowed to fully retract into the cage housing. In a fully retracted position, the rolling supports remain partially protruded from the cage housing. This allows the rolling supports to act as rolling bearings between the cage housing and tubular surface aiding in the entering and or exiting of a tubular.
A ninth disadvantage of previous attempts is in the design of the member containing the inclined or tapered ramps which include areas of deeper than necessary pockets as well as sharp corners. It is known that sharp edges or corners should be eliminated where possible to remove stress concentration areas as well as areas increasing the potential for cracking. These sharp corners also create areas prone to corrosion and or rusting.
A tenth disadvantage of previous attempts is in the use of multiple components such as small springs, plungers, inserts, biasing devices, etc which are all made unnecessary by the embodiments of the present invention. All of these components must be held in place via means such as press fitting, adhesives, threaded fasteners, etc. which all initiate the potential for failures. It is well known that as the number of parts is increased for a single mechanical device so does the odds of failure. The corresponding machining or manufacturing processes for these components is greatly complicated by the use of these components. The complexity and tight tolerances required to successfully manufacture these components substantially increases the overall cost of the gripping device.
An eleventh disadvantage of previous attempts again in the use of multiple components such as small springs, plungers, inserts, biasing devices, etc is that should any of these small components become loose or free from constraint, they can potentially fall into the wellbore. This potential is very high due to the jarring and shock loads the gripping device will experience in service as well as transport. These shock loads can loosen threaded fasteners or other means of retention. Also, heat and or extreme cold can affect retention means such as adhesives, press fit and interference fit tolerances. Should any of these components become free from constraint, the elongated slots will allow these items to depart from the assembly, thereby becoming major safety hazards with the potential for serious damage to personnel or structures from flying debris. Materials or items which unintentionally fall into the wellbore create an array of very costly problems.
A twelfth disadvantage of the previous attempts utilizing the aforementioned inserts which are press fit or otherwise attached to the member containing the inclined surfaces is in the non destructive testing of these components after each use in the field.
It is well known in the oilfield industry that after each use, all load carrying tools must be completely disassembled, cleaned, and inspected for cracks, wear, damages, or anything else that may prevent a tool from functioning properly or possibly failing in service. Components which are press fit or adhered using adhesives are generally very difficult or impossible to remove for inspection purposes. This means that these parts will likely not be removed thereby possibly hiding a crack or damage. If a threaded fastener is used, these threads create stress risers and areas for corrosion to begin.
The intention of the present invention is to offer a much improved apparatus and method of running tubular OCTG into or out of a borehole vastly improving the safety, efficiency and torque capability without the shortfalls in the tools available today.